Such a storage system coupled to a gas turbine is known for instance from US 2011/0094236 A1. Said patent proposes storing compressed air in a cavern when excess electrical power is available. Before the process of storage in the cavern, heat is extracted from the compressed air, to feed this heat thereafter once again to the compressed air when the latter is removed from the cavern and supplied to a combustion chamber of a gas turbine.
In addition, US 2010/0146981 A1 teaches interconnection of a gas turbine which may thermally condition the intake air of a gas turbine to higher and lower temperatures using a heat exchanger. In this case, the heat exchanger may be provided with thermally conditioned water, which may also be removed from a cold tank for cooling purposes.
Owing to the increasing proportion of electrical energy supplied by fluctuating renewable energy sources in public power supply networks, gas-fired power stations or combined-cycle power stations are increasingly only used as backup power stations or for network stabilization. These power stations are operated in particular at times of lower energy provision by renewable energy sources, to ensure electrical power supply. As a result of this growing trend, these power stations are increasingly operated under partial load, i.e. in a load state for which the power stations are mostly not optimally designed. Owing to the non-optimal technical design of gas turbines, fuel-related efficiency in partial load operation is lower than under full load.
As a result of this disadvantage, it is desirable to improve gas turbines with regard to their flexibility in such a way as to increase partial load efficiency with regard to fuel consumption. Such a flexibility-enhancing measure should also make it possible when necessary to start up the gas turbine more quickly, over shorter start-up times. In this case it should be borne in mind that, during start-up operation, the gas turbine has likewise to be operated under partial load over a limited period before it can be run in the full load state which is advantageous with regard to efficiency. An improvement in partial load operation should however as far as possible also be undertaken in an energy-efficient manner, without solely using valuable primary energy.
Furthermore, it is also desirable to equip existing gas turbines for such improved flexible operation through simple structural modifications.